Both national legislation and international regulations put in place by
the International Maritime Organization within the framework of the international
Marpol Convention function through checks for compliance. Marpol came into
force in 1983 and its annexes are constantly being revised. The convention
states that all vessels must possess a certificate of compliance defining
a set of standard safety techniques. In the event of non-compliance, the
vessel may be banned from leaving port by inspectors from its State of registration
(Flag State) or the State
in which it puts into port (Port State).

In order for checks to be more effective, the European countries signed
a Memorandum (known as the Paris Memorandum) in 1982 which introduced a
common vessel inspection system and set minimum check quotas. The Erika
and Prestige accidents highlighted the lack of these checks in certain countries,
due to an insufficient number of inspectors.